|
Many environmental issues affecting both aquatic and terrestrial environments in Tasmania are consequences of human-induced changes to land cover. Tracking changes to land use and land cover is important as they are significant drivers (and signals) of change in the environment. Land tenure, land use and land cover decisions and allocations have fundamental social, economic and environmental implications. Land tenure also helps to define rights and responsibilities in relation to land use: National Parks and other formal and informal reserves, for example, confer greater levels of protection against land cover change and loss of habitat than private land. Land cover refers to the physical state of the land surface and includes vegetation, soil, rock, water and man-made structures. Land cover is the cumulative consequence of human influence and ecological processes over many thousands of years. Aboriginal land management practices strongly influenced vegetation cover: fire was used by Aboriginal people to alter habitat and increase food supply as well as for cooking, warmth and social uses such as signalling and warfare. More recent land management decisions have extensively modified land cover. Land cover change is a result of land management decisions that are influenced by market forces and land tenure classifications. Definitions of land tenure are also continually evolving as they are influenced by legislation and public values. Land clearance is one of the significant forces of change and this issue is discussed in more detail in the Biodiversity Chapter. Natural systems are in a state of dynamic equilibrium that has taken many thousands of years to evolve. Maintaining areas where natural rates of change can occur is vitally important so we might better know how systems function. Change is significant when it causes loss of biodiversity, reduction of landscape values or loss of ecosystem services such as clean drinking water. Tree decline in the Midlands is perhaps the clearest example in Tasmania that highlights how change may take years to manifest itself as an environmental problem, by which time, it may be difficult and costly to retrieve 'natural' ecosystem functions. How is it possible to determine whether changes to land cover are significant? Comparisons with pre-European vegetation cover provide a perspective on change over a long time-frame. Other perspectives can be provided through comparisons with areas that have remained substantially unmodified that are subject to natural rates of change or with land cover as it was five years previously. The 'significance' of change depends on the on-the-ground context in which the changes are occurring. The Tasmanian Bushcare Network has provided some of this local context through case studies of local environmental issues. Land cover change is also an indicator of land use change. Clearance rates of woody vegetation can be used as a surrogate measure for changes in land use as woody vegetation is cleared or modified to accommodate specific land uses (NSW EPA 2001). Land cover changes can affect a wide range of processes such as the movement of nutrients through plants, soil, water and the atmosphere, the emission of greenhouse gases and the movement of soil and water within catchments (State of the Environment Advisory Council 1996). Land cover change can have major consequences for biodiversity and these changes are discussed in more detail in the Biodiversity Chapter. Describing how land is used, the relationships between land use and society, economy and environment is often complex and can defy description. Nevertheless, one of the objectives of the NLWRA was to describe some of these relationships nationally. The NLWRA identified fluctuating prices for commodities, particularly over extended periods, as a primary driver to land use change. This is clearly the case in Tasmania where economic returns available on plantation forestry have been a significant economic driver for rates of plantation development. Private Forests Tasmania (2001) reports regularly on indexed prices for rural commodities through its market report. Prices for many farm commodities have been collected and indexed for six years leading up to 1999-00. The five top performing rural commodities, by price, were poppies, fat lambs, category 2 sawlogs and category 1 and 3 sawlogs off Crown land and run of the bush sawlogs from private land. ('run of the bush' is a term used to refer to a single price being paid for sawlogs as they come off the land without being segregated into separate sawlog categories.). Economic returns and employment are some of the benefits of the land use and land cover decisions that are described in the following section. For example, private forests cover 14% of the total land area of Tasmania, however they account for almost half the total timber production each year. Private forests are a critical source of wood supply to the timber processing industries, which, combined with forestry, are the second largest manufacturing industry in Tasmania in terms of income generation (Private Forests Tasmania 2001). Regional perspectives of land cover can be seen through Landsat satellite images of Tasmania. Land cover is an outcome of the interaction of environment, land use and tenure over many years and evidence of this interaction is apparent in these images. Tasmania's diversity of landform and vegetation has itself conferred some protection against land cover change. Although very small in area compared to mainland Australia, Tasmania has a remarkably varied geology, a wide range of landforms, and the most mountainous terrain on the continent. The environment, particularly the diversity of soils, landscapes, vegetation and terrain in Tasmania, has influenced the regional pattern of land use and land cover. Large scale clearing for agriculture has occurred mostly on the better soils and gentler slopes. This diversity in the Tasmanian landscape is reflected in the variety of vegetation types found across the State. Major vegetation ecosystems range from buttongrass moorlands and dense rainforests of western Tasmania, to alpine vegetation in the highlands; tall eucalypt forests in more fertile, wet areas, grasslands and grassy woodlands in the Midlands and drier eastern areas, and the saltmarshes, heathlands and wetlands along the coastal fringes. The type of land use undertaken in certain regions is often dependent on the economic returns available. Economic returns are currently the major commercial influence on the demand for the establishment of forest plantations on relatively moist sites, particularly in the north-west, north-east and south. This pattern is shown in the map of woody vegetation change. Dairying is also another land use activity influencing changes in land cover with clearance of native vegetation cover for pasture occurring in the north-west and north-east. As a result of their status as National Parks or reserves, some areas have had comparative land cover stability, allowing natural rates of change to occur. These areas of relative stability are also evident in the map of woody vegetation change.
Assessing and measuring the current situation Land cover change is a widespread feature of human interaction with the environment. Changes can occur rapidly such as in the case of clearance or harvesting, or take place over the long-term as a result of natural or human induced influences. Keeping track of changes in land cover and land use is complex and reliant on a variety of data sources and measures. Key information sources include: TASVEG, satellite data for change detection, building completions, and ABS Agricultural Census data, and Forest Practices Board Annual Reports on Harvested Area. Land tenure is maintained by the State Government as a core dataset of the LIST. Woody vegetation change is used in this SoE Report as a surrogate measure of land cover change. |
||||||||||||||||
|
Land Use - at a glance
|
|||||||||||||||
|
Land Cover - at a glance
|
||||||||||||||||
|
New Dwelling Completions - at a glance
|
|||||||||||||||
|
Because land use, land cover and land tenure decisions and allocations have fundamental social, economic and environmental implications, management responses to these issues are many and varied. They include those relating to: Many of these responses are discussed in more detail in other sections of this SoE Report. For example, changes to the reserve system, which influence land use and land cover, are discussed more fully in Reservation. Tasmania Together and the RMPS Relevant Tasmania Together goals and standards for 'Land' are listed in the linked file. The Tasmania Together Progress Board reported on progress toward targets for benchmarks set (Tasmania Together Progress Board 2003). Indicators, targets and baseline data are available in the latest Progress Report June 2003. Further information, including progress report updates, is available from Tasmania Together. Involvement of the community, and the fair and orderly use of resources are also fundamental principles of the RMPS. The RMPS objectives have been developed to advance the principles of sustainable development.
|
||||||||||||||||
